Background and Objectives: Previous studies have evaluated the diagnostic effect of amyloid PET in selected research cohorts. However, these studies did not assess the clinical impact of the combination of amyloid and tau PETs. Our objective was to evaluate the association of the combination of 2 PETs with changes in diagnosis, treatment, and management in a memory clinic cohort.Methods: All participants underwent amyloid [18F]florbetaben PET and tau PET using [18F]PI-2620 or [18F]Florzolotau, which are potentially useful for the diagnosis of non-Alzheimer disease (AD) tauopathies. Dementia specialists determined a pre- and post-PET diagnosis that existed in both a clinical syndrome (cognitive normal [CN], mild cognitive impairment [MCI], and dementia) and suspected etiology, with a confidence level. In addition, the dementia specialists determined patient treatment in terms of ancillary investigations and management. Results: Among 126 registered participants, 84.9% completed the study procedures and were included in the analysis (CN [n = 40], MCI [n = 25], AD [n = 20], and non-AD dementia [n = 22]). The etiologic diagnosis changed in 25.0% in the CN, 68.0% in the MCI, and 23.8% with dementia. Overall changes in management between pre- and post-PET occurred in 5.0% of CN, 52.0% of MCI, and 38.1% of dementia. Logistic regression analysis revealed that tau PET has stronger associations with change management than amyloid PET in all participants and dementia groups. Discussion: The combination of amyloid and tau PETs was associated with changes in management and diagnosis of MCI and dementia, and the second-generation tau PET has a strong impact on the changes in diagnosis and management in memory clinics. Classification of Evidence: This study provides Class I evidence that the combination of amyloid and tau PETs was associated with changes in management and diagnosis of MCI and dementia.
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